Because bots can't read game information...
This is close. Basically, Battlegrounds are pretty lenient on who they reward. If you win, your entire team gets credit for the reward. If you lose, your entire team still gets some credit.
If they set it up, so that every point of damage dealt, healed (discounting overhealing), PVP objectives helped captured and defended, and winning/losing gave you +/- 10% or so, you couldn't really make a bot who charges midfield, /dance, gets killed, respawn and repeat. If he does 0 damage, carries 0 flags, defends 0 flag carries, and heals 0 damage, he gets 0 honor.
I understand the team mentality, where if someone gets stuck defending farm, a tower in AV, whatever. They may not see a whole lot of action. It makes sense to have defendable nodes give honor, with the honor diminishing with each extra person there (imagine, AB starts, everyone captures farm and camps it for honor. lol)
This is also not a bad idea, because it'd prevent turtles.
Ok, obviously many people aren't reading past the OP before opining. So as a PSA:
This idea has already had three methods to defeat a captcha, either as Op described or more traditional version. Two of which were actually given in detail exactly how they would work. These systems for defeat are already in use for various parts of automating the game, like fishing, and would take less than a day to implement. this implementation would be done on the PTR. Meaning by the time this change went live, bots would already have their work around.
This system will stop 0% of the bots, inconvenience 100% of legit players.
It's "broken by design" as it only affects the people who use it legitimately. The same way DRM only affects people who buy the game/movie/music and has no effect on the pirates.